Separations of polynucleotides such as DNA have been traditionally performed using slab gel electrophoresis or capillary electrophoresis. However, liquid chromatographic separations of polynucleotides are becoming more important because of the ability to automate the analysis and to collect fractions after they have been separated. Therefore, columns for polynucleotide separation by liquid chromatography (LC) are becoming more important.
Silica-based columns are by far the most common LC columns. Of these, reverse phase silica-based columns are preferred because they have high separation efficiencies, are mechanically stable, and a variety of functional groups can be easily attached for a variety of column selectivities.
Although silica-based reverse phase column materials have performed adequately for separating single stranded DNA, these materials have not performed well for separating double stranded DNA. The peaks from double stranded DNA separations using silica-based materials are badly shaped or broad, or the double stranded DNA may not even elute. Separations can take up to several hours, or the resolution, peak symmetry, and sensitivity of the separation are poor.
High quality materials for DNA separations have been based on polymeric substrates, as disclosed in U.S. Pat. No. 5,585,236 to Bonn (1966). There exists a need for silica-based column packing material and other materials that are suitable for separation of double stranded DNA.